Generalized lighting vs localized lighting

Generalised (general) lighting is a scheme in which luminaires are arranged in a regular pattern over the whole area to give a uniform level of illumination on the working plane, regardless of where the work is done. It lights tasks, gangways and surroundings alike.

Example: a classroom or a textile weaving shed lit by rows of LED panels/tube fittings at equal spacing to give about 300 lux everywhere.

Why localised lighting cannot be used alone

Localised lighting puts lamps close to particular work points (machine lamp on a lathe, bench lamp). If it is the only lighting:

1. High contrast and eye fatigue: the eye moves between a very bright task and dark surroundings and keeps re-adapting, which causes strain and headache.
2. Safety hazard: gangways, stairs, moving cranes and obstacles stay dark, so workers may trip or collide; finding exits in an emergency is difficult.
3. Harsh shadows and glare: a single nearby source throws deep shadows and may reflect off shiny work.
4. Poor supervision and cleaning: the general area cannot be inspected or maintained easily.
5. Gloomy, unpleasant environment that lowers morale and productivity.

Example: in a machine shop, a lamp on each lathe gives 1000 lux on the tool, but a worker walking between machines with no general light cannot see oil spills or moving trolleys. So local lighting is always used with general lighting (general-plus-local scheme), with the general level at least about one-third of the local task level.